Zigmont purchased 1000 gallons of gasoline for his service station from Oakwood Energy Products for $2.49 per gallon. Zigmont later learned that all other gas suppliers in the city charged only $2.29 per gallon. Zigmont sent a check to Oakwood for $2,2900.00 with the notation, "In full payment for the 1000 gallons of gasoline purchased from your company." Oakwood deposited the check. What are Oakwood's legal rights, if any